Many thanks to the SatNOGS Network, AMSAT and all the Radio Amateurs all around the world for their precious support!
STECCO operates on the amateur radio frequencies in the UHF band.
STECCO hosts a radioham digipeater which is active by default and can be accessed by any radioamateur. Instructions for the use of the digipeater are reported below.
In addition any radio amateur is invited to receive the satellite telemetry and share it at his will. Instruction for decoding the telemetry data packets are reported below.
Data received by the radio-amateur community around the world will be collected and sorted along with data downloaded by the Ground Station of the School of Aerospace Engineering. All the data will be available for free consultation online and all the contributors will be acknowledged.
Radio link
Radio Frequency Band: UHF
Downlink Frequency: 435.800 MHz
Uplink Frequency: 435.800 MHz
Modulation: 9600 baud FSK
Encoding: G3RUH
Protocol: ax.25
STECCO Beacon
STECCO sends periodic beacon messages containing status and telemetry information.
There are three types of message with different length that are sent with different periodicity also according to the satellite operational mode.
MCU Beacon (218 bytes) contains configuration and status information along with a text message field.
FPGA Beacon (184 bytes) contains mainly status and telemetry data including events, real-time-clock, temperature and IMU data. Last 120 bytes, from 64 to 183, contain 10 samples of magnetometer and gyro readings. The image below only shows the first sample: the following bytes replicate the same structure of bytes from 64 to 75.
RADIO Beacon (37 bytes) contain basic information like RSSI, number of received and transmitted bytes and number of errors..
The detailed structure of the beacon messages is reported below (click on the images to download the text-selectable PDF version) along with the instructions to decode them. An example of each beacon is also reported below.
MCU Beacon
FPGA Beacon
Radio Beacon
Examples of STECCO beacon messages.
MCU Beacon
a6 a8 8a 86 86 9e 06 92 aa 60 a6 92 82 06 03 f0
53 54 45 43 43 4f 20 50 48 4f 45 42 45 20 4d 43
55 0d 00 00 00 03 b2 01 0b 05 36 06 00 01 01 14
64 00 f0 02 10 7a 00 44 00 eb 07 36 09 ad 05 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 0a 00
00 00 00 00 00 00 00 0d 00 0d 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 0a 50 00 00 00 00 01
00 00 00 31 46 0a 00 c4 4d 00 00 c2 07 00 00 83
2e 00 00 7d 0a 3d 0c 48 52 22 c1 83 2e 00 00 03
00 02 02 53 63 68 6f 6f 6c 20 6f 66 20 41 65 72
6f 73 70 61 63 65 20 45 6e 67 69 6e 65 65 72 69
6e 67 20 53 61 70 69 65 6e 7a 61 20 55 6e 69 76
65 72 73 69 74 79 20 6f 66 20 52 6f 6d 65 00 00
00 00 00 01 00 d4 05 01 00 1c
FPGA Beacon
a6 a8 8a 86 86 9e 06 92 aa 60 a6 92 82 06 03 f0
15 53 54 45 43 43 4f 92 aa 60 a6 92 82 2b 06 01
00 42 f0 ff 07 3f 1f ff 00 00 a7 ff 06 90 e8 b7
1c 06 00 80 18 80 18 80 00 14 00 00 00 00 10 01
55 fa 3f 10 b4 ff 23 00 3e ff a2 00 35 fa 65 10
fe ff 16 00 39 ff a4 00 2d fa 53 10 bf ff 1a 00
3c ff a2 00 6b fa ef 0f ef 00 1c 00 34 ff 9e 00
89 fa b5 0f 52 00 1c 00 38 ff a2 00 57 fa a5 0f
c2 00 26 00 3f ff ab 00 35 fa 67 10 eb ff 1e 00
42 ff a9 00 79 fa c3 0f 07 01 26 00 40 ff a6 00
17 fa 6f 10 cc ff 21 00 44 ff a4 00 25 fa 4d 10
24 00 1a 00 44 ff ab 00
Radio Beacon
a6 a8 8a 86 86 9e 60 8e 82 aa a6 a6 40 61 03 f0
00 00 03 11 f5 02 00 00 00 03 00 00 00 05 00 00
00 00 00 00 00
STECCO Digipeater
The satellite will reply to an incoming radioamateur packet by resending it to ground using as destination address in the ax.25 header the callsign of the radioamateur that made the uplink.
The last radioamateur callsign is also included in the beacon message of the satellite and the list of all the radioamateur callsigns that made an uplink will be stored on board and, once downloaded, it will be published here.
The digipeater function can be occasionally disabled in case of particular situations which could harm the satellite operational life.
To use the digipeater you just need to send an ax.25 data packet containing the digipeater command (°°°°°°) followed by the message that will be broadcasted after 2 seconds. A dead time of about 8 seconds is then applied before next digipeater uplink is accepted to cope with the limited power budget of such a small satellite.
We suggest to use the KISS protocol. Please note that the on-board software was developed according to this structure therefore the source and destination fields are swapped with respect to the official ax.25 header. Anyway the 1-bit left-shift of the callsign bytes is used as requested by the protocol. In addition, the SSID fields are also a bit unconventional due to a software bug that was discovered too late to be fixed: you need to put 0x01 and 0x06 respectively.
An example of a KISS string is:
KISS begin:
0xc0
TNC:
0x00
Source callsign (all bytes left-shifted by one bit; e.g.: "I" -> ASCII 0x49 -> 0x92):
0x** 0x** 0x** 0x** 0x** 0x**
SSID:
0x01
Destination callsign:
0xa6 0xa8 0x8a 0x86 0x86 0x9e
SSID:
0x06
Control field:
0x03
PID:
0xf0
Digipeater command:
(will be published after launch)
Message (e.g. CIAO):
0x43 0x49 0x41 0x4f
KISS end:
0xc0
Putting all together:
0xc0 0x00 0x** 0x** 0x** 0x** 0x** 0x** 0x01 0xa6 0xa8 0x8a 0x86 0x86 0x9e 0x06 0x03 0xf0 0x°° 0x°° 0x°° 0x°° 0x°° 0x°° 0x43 0x49 0x41 0x4f 0xc0